1. Field of the Invention
The present invention relates to vertical take-off aircraft generally and, more particularly, but not by way of limitation, to a ball wheel for such an aircraft.
2. Background Art
Vertical take-off aircraft are useful in various situations in which horizontal space is limited. Aircraft are well known means of air transport. Among conventional aircraft are: common airplanes with fixed wings, helicopters with rotating wings, common airplanes with tilting rotors (Osprey), gyrocopters with freely rotating wings creating lift by spinning because vehicle is pushed with regular horizontal motor with propeller, fighter jets with adjustable thrust downwards for takeoff and horizontal thrust to fly (Joint Air Strike Fighter), rockets, and disc-shaped aircraft with internal engine exhaust blowing over airfoil to create lift.
A disadvantage of many of these conventional aircraft is that they require a relatively long horizontal distance to take off. Others, such as rockets, are unsuitable for general use.
The Osprey suffers from the disadvantage that it has only a lift force or a push force by propellers and during transitional flight, this force is divided. Because of the tilting of the propellers, the vehicle bearing low pressure disc (created by the propellers) gets much smaller and is divided into a vertical part and a horizontal part. But the vertical part needs enough bearing capacity to lift. This is resolved by providing oversized propellers—more than necessary—and this requires more than necessary engine power that is not efficient. Huge propellers are not efficient and are disturbing for straight level flight. During the tilting process, the propellers cut through the downwards directed air stream, reduce efficiency, and make the aircraft very shaky and unsecured. The tilting rotating masses create a gyroeffect and make it very hard to stabilize the aircraft, one movement creating another effect and so on. Sometimes the aircraft is impossible to control and it falls down.
Some attempts to provide such an aircraft include the following:
U.S. Pat. No. 2,859,003, issued Nov. 4, 1958, to Servanty, and titled AERODYNE, describes a vertical take-off aircraft that has three equally spaced engines spaced apart from the base of a fuselage by vertical wings. Three vertical winglets are disposed near the top of the fuselage. The fuselage is generally bullet-shaped.U.S. Pat. No. 3,045,951, issued Jul. 24, 1962, to Freeland, and titled AIRCRAFT, describes an aircraft in which the four engines thereof are disposed within a fuselage that slopes inwardly and downwardly from a dome-shaped upper portion, but the lower portion is flared outwardly at the bottom thereof.U.S. Pat. No. 3,120,359, issued Feb. 4, 1964, to Sprecher, and titled AIRCRAFT WITH EQUI-SPACED POWER PLANT, describes an aircraft that has four equally spaced engines disposed at an upper end of a fuselage and joined thereto by wings and four interposed wings disposed at a lower end of the fuselage and bearing at their distal ends landing gears. The fuselage is generally bullet-shaped.U.S. Pat. No. 3,252,673, issued May 24, 1966, to Reichert, and titled SUPERSONIC VTOL AIRCRAFT AND LAUNCH VEHICLE, describes an aircraft having two engines disposed on the outside of a cylindrical shroud disposed in approximately the middle of a bullet-shaped aircraft, the shroud being supported from the aircraft by struts. Three wings are disposed at a lower end of the fuselage.U.S. Pat. No. 4,123,018, issued Oct. 31, 1978, to Tassin de Montaigu, and titled HELICOPTER WITH COAXIAL ROTORS, OF CONVERTIBLE TYPE IN PARTICULAR, describes a helicopter that is clearly non-symmetrical.U.S. Pat. No. 4,433,819, issued Feb. 28, 1984, to Carrington, and titled AERODYNAMIC DEVICE, describes a rotatable disk affixed to a central, generally dome-shaped body, the disk including a plurality of selectively vectorable jets. A plurality of reaction jets are attached to the central body.U.S. Pat. No. 5,178,344, issued Jan. 12, 1993, to Dlouhy, and titled VTOL AIRCRAFT, describes, insofar as pertinent, a disk-shaped aircraft having a plurality of rotating sets of rotor blades disposed at least partially beneath the disk. The rotor blades may be pivotable to provide for horizontal motion of the aircraft.U.S. Pat. No. 5,595,358, issued Jan. 21, 1997, to Demidov et al., and titled MULTIPURPOSE AIRBORNE VEHICLE, describes an aircraft having a plurality of rotor units disposed below a ring-shaped fuselage. U.S. Pat. No. 5,839,691, issued Nov. 24, 1998, to Lariviere, and titled VERTICAL TAKEOFF AND LANDING AIRCRAFT, describes such an aircraft that is clearly not symmetrical about its vertical axis.U.S. Pat. No. 6,293,491, issued Sep. 25, 2001, to Wobben, and titled VERTICAL TAKE-OFF AND LANDING AIRCRAFT, describes another such aircraft that is clearly not symmetrical about its vertical axis.